Sorry I have taken a while to respond. Unfortunately I will be away from my Debian boxes until monday, so I can't start investigating your suggestions before then.
Meanwhile perhaps we can come a little further with some questions. It seems rsync could be needed for your solution? (Sorry, I'm not very technically intelligent.) One thought I had was: would it work simply copying the /var/cache/apt tree to a CD, mount that CD on /var/cache/apt, and get dselect to use the contents on the CD that way? Would that require the same Internet source in sources.list that I used on the first computer to fetch and install the first time? I.e. would an Internet connection be needed on subsequent installs on the other computers? One problem I thought of with installing from a "real" installation CD would be that the packages would be cached on the new computer also. In my case I can not be sure that there will be enough space on the harddisc for that. Hence the above idea. Hope this sets some things in motion at your end. Best regards Johnny :o)
